Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261604AbUCVBeF (ORCPT ); Sun, 21 Mar 2004 20:34:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261611AbUCVBeF (ORCPT ); Sun, 21 Mar 2004 20:34:05 -0500 Received: from holomorphy.com ([207.189.100.168]:16270 "EHLO holomorphy.com") by vger.kernel.org with ESMTP id S261604AbUCVBeD (ORCPT ); Sun, 21 Mar 2004 20:34:03 -0500 Date: Sun, 21 Mar 2004 17:28:22 -0800 From: William Lee Irwin III To: Jeff Garzik Cc: rmk@arm.linux.org.uk, Linus Torvalds , David Woodhouse , Christoph Hellwig , Andrew Morton , Andrea Arcangeli , linux-kernel@vger.kernel.org Subject: Re: can device drivers return non-ram via vm_ops->nopage? Message-ID: <20040322012822.GA2045@holomorphy.com> Mail-Followup-To: William Lee Irwin III , Jeff Garzik , rmk@arm.linux.org.uk, Linus Torvalds , David Woodhouse , Christoph Hellwig , Andrew Morton , Andrea Arcangeli , linux-kernel@vger.kernel.org References: <20040321204931.A11519@infradead.org> <1079902670.17681.324.camel@imladris.demon.co.uk> <20040321222327.D26708@flint.arm.linux.org.uk> <405E1859.5030906@pobox.com> <20040321225117.F26708@flint.arm.linux.org.uk> <20040321234515.G26708@flint.arm.linux.org.uk> <20040322002349.GZ2045@holomorphy.com> <405E3387.1050505@pobox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <405E3387.1050505@pobox.com> User-Agent: Mutt/1.5.5.1+cvs20040105i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1336 Lines: 26 On Sun, Mar 21, 2004 at 07:29:59PM -0500, Jeff Garzik wrote: > No comment on struct dma_scatterlist, but the above is the most natural > API for audio drivers at least. > Audio drivers allocate buffers at ->probe() or open(2), and the only > entity that actually cares about the contents of the buffers are (a) the > hardware and (b) userland. via82cxxx_audio only uses > pci_alloc_consistent because there's not a more appropriate DMA > allocator for the use to which that memory is put. > Audio drivers only need to read/write the buffers inside the kernel when > implementing read(2) and write(2) via copy_{to,from}_user(). I based it on rmk's set of arguments to his functions; I'm hoping for feedback (or another API/implementation) from him and hopefully at least one other arch maintainer having problems in this area. I'm hoping to focus mostly on the driver sweep, and to devolve e.g. finer details of the design like the above arguments and/or structures to those with more detailed knowledge or direct experience (and the broader details came from elsewhere too). -- wli - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/